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Abstract:

The present disclosure provides a means to build a solar cell that is
transparent to and polarizes visible light, and to transfer the energy
thus generated to electrical power wires.

Claims:

1. A method of making a photovoltaic diode composed of multiple doped
thin films layers creating a photoactive diode on a substrate yielding a
transparent window.

2. The substrate in claim 1 is comprised of a transparent glass
substrate.

3. The thin film layers in claim 1 are comprised of doped and undoped
layers creating a p-n or a p-i-n junction forming the photovoltaic
device.

4. The wiring in claim 1 is comprised of conductors, semiconductor
materials, or a combination thereof. A method to use transfer the energy
generated by this photovoltaic cell to electrical power wires.

4. The window in claim 1 has a DC to AC converter and the window is
electrically connected to the converter.

5. A method of making a photovoltaic diode composed of multiple doped
thin films layers creating a photoactive diode on a substrate yielding a
transparent polarized window.

6. The substrate in claim 5 is comprised of a transparent glass
substrate.

7. The thin film layers in claim 5 are comprised of doped and undoped
layers creating a p-n or a p-i-n junction forming the photovoltaic
device.

8. The wiring in claim 5 is comprised of conductors, semiconductor
materials, or a combination thereof. A method to use transfer the energy
generated by this photovoltaic cell to electrical power wires.

9. The wiring in claim 5 is arranged in such a manner to create light
polarization if the window.

10. The window in claim 1 has a DC to AC converter and the window is
electrically connected to the converter.

11. The wiring in claims 4 and 8 is comprised thin metal wires that are
20 nm to 200 nm wide. These lines correspond to the wavelength of light
to be absorbed.

12. The width of the spacing between the wiring in claims 4 and 8 is 20
nm to 200 nm.

13. The spacing of the wiring in claim 11 and the width of the wiring in
claim 12 can be tuned to optimize the energy produced.

14. The spacing of the wires and the transparent spaces in claims 11 and
12 can be varied, they can be uniform between all lines or can vary in
width, with various wire widths and carious spacing widths.

15. The wiring in claim 11 can be nanowires, nanotubes, metal paint,
molecular imprint, or other method to produce nanometer-length wiring.

16. The thin film in claims 3 and 7 is composed of a material that is
transparent when it configured as a thin film. Possibilities include but
are not limited to SiO2, TiN, TCO, CdTe, polySi, and organic films.

17. The thin film in claims 3 and 7 can be deposited by CVD, including
PECVD, MOCVD, ALD or other similar method or PVD, sputtering, or other
similar methods, or electroplating, screen printing or other similar
method.

Description:

[0001] The present invention is a continuation of provisional patent
61/315,396.

FIELD OF THE INVENTION

[0002] The present invention relates to apparatuses and methods to produce
solar cells.

BACKGROUND OF THE INVENTION

[0003] Solar cell, also known as photovoltaic cell, technology is
increasingly useful as energy costs and people seek environmentally
friendly "green" ways to generate power. However, current solar cells are
opaque, limiting their use in commercial and residential building to
rooftop installation with no functionality other than creating energy.
This precludes their use in a variety of applications that require
transparency. In particular if solar cells were transparent they would be
useful as windows. Since glass windows are a common feature to may
building, both commercial and residue, windows that can be made both to
generate energy and to allow illumination into the building are
beneficial. Windows are extremely common and are found on all types of
building; homes, apartments, office, and other institutions; both
vertically installed and horizontally, such in skylights. Additionally,
dual uses as a polarized and solar window would be useful for shading,
darkening, and for energy generation.

[0004] Until this invention, no other patent has disclosed the ability to
provide solar power with a transparent and viewing window for energy
generation.

[0005] The usefulness of using windows for solar cell has been a goal for
many researchers. Solar windows have been disclosed that integrate solar
cells in the window itself, in a decorative pattern or as a replacement
for glass panels. U.S. Pat. No. 4,137,098 discloses an array of solar
cells in a Venetian blind configuration which can be opened or closed to
let in light. U.S. Pat. No. 5,128,181 discloses a combination of solar
cell and solar heating panel integrated together. U.S. Pat. No. 6,646,196
discloses a simple arrangement of window panes and a solar cell panel
installed in a frame that can be placed in a window opening, the same
panel that can be installed on roof-tops. All these inventions integrated
silicon wafer solar cell technology arranged to create windows, but the
solar cell is not the window itself. Limitations arise as to the amount
of light that can be allowed into the room where the window is.

[0006] U.S. Pat. No. 6,688,053 shows a double paned, solar power window
that encloses solar cells and dichromatic minors between the two panes,
thus using the reflected light to generate electricity. This patent
combines three functions into one, relying on integration of these
components. The light directed to the solar cells relies on dichromatic
mirrors to direct all wavelengths of light to mirror. The cells are
arranged in a manner to allow light into the building while also
generating electricity. A converter is required to transform DC to AC.
The physical dimensions are not disclosed, but the thickness of the
window is assumed to be of the order of an inch and may be limited for
residential applications. Also, the integration is quite costly and
required three separate components. Also of limitation is the light
allowed into the room.

[0007] U.S. Pat. No. 7,019,207 discloses a thin film solar panel that
could be used for window applications, the etched transparent lines act
as Venetian blinds allowing light to enter a room, providing partical
shade. However, the blinds cannot be modulated, they are permanent
fixtures. Because patterns can be etched into the thin film windows were
shading is required or a decorative facade can be fabricated. Limitation
of this application is the light that is allowed into the room.

SUMMARY

[0008] In an embodiment the present invention discloses a method to build
a "solar window", a device that is transparent, lets in light for
illumination, and allows viewing of the surrounding area, but still
generates electricity from light. The solar window, as exemplified in
[FIG. 1], is a device that comprises parallel strips of: [0009] 1.
Optically opaque photovoltaically active material [0010] 2. Optically
opaque "wire", i.e. electrically conductive material [0011] 3. Optically
transparent material.

[0012] These strips have characteristic widths similar to one quarter of
the wavelengths of visible light. The strips may have all the same width,
or may have different widths. The strips are not visible with the naked
eye, and thus do not impede the view through the transparent glass
substrate.

[0013] The percentage of the total width of the whole solar window that is
photovoltaic active material is linearly proportional to how much power
the solar window generates.

[0014] The percentage of the total width of the solar window that is wire
is linearly proportional to the maximum current the solar window can
generate, and thus limits the maximum power the solar window will
generate in practice.

[0015] The percentage of the total width of the whole solar window that is
transparent linearly determines how much visible light can cross it, and
thus how "dark" it is.

[0016] That the transparent parts of the solar window are parallel and
approximately the wavelength of visible light which causes the solar
window to be a polarizing grid, i.e. transparent to the naked human eye.
Also this arrangement causes the photovoltaic cell to polarize light,
like polarizing sun glasses. Simultaneously the solar window generates
electrical power when exposed to light.

[0017] In an embodiment the solar window may have a transparent coating to
protect the photosensitive materials.

[0018] In another embodiment, the solar panel is a frameless unit that
want be placed into a window opening, which is framed.

[0019] In one embodiment, the solar panel and is connect to the power
supply through external wiring.

[0020] If the windows of a building consist of solar windows then those
windows become solar photovoltaic cells, thus generating electrical power
during daylight hours. Moreover such windows are polarized, thus blocking
glare from the sun. Those windows also are transparent and allow a view
of the surrounding area.

[0021] To integrate the windows into the grid or power supply generation
for the building successfully power generated from the window must be
conductor to the point use, through the supply line. The distribution box
is typically placed close to the panels. However, the need for embedding
the windows directly into the building circumvents this arrangement.
Thus, the inverter can be installed in the wall between joists, and
conducted to any part of the house through conventional wiring. Windows
can be wired in series and can be grounded, and surge protectors added as
needed.

[0022] U.S. Pat. No. 6,750,391 discloses an elegant solution for windows
that needs only simple wiring from each window to the inverter and
supporting electronics that could also be used. This arrangement would be
very practical for a residential dwelling or small commercial building.
On a larger scale, series of these modules could be employed.

[0023] Alternate wiring and generation schemes are possible with the same
result. For instance a local battery for storing energy for use at night.
How this power is stored is outside of the scope of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 shows an exemplar of the solar window. The transparent
material (1), photovoltaic material (2) and electrically conducting
material aka wire (3) are all in parallel strips. At the edges of the
solar window, perpendicular to these strips, are the side bars. These
contain circuitry to accumulate and to use the current generated in (2)
and carried in (3).

[0025] FIG. 2 shows a cross section of a photovoltaic device on a solar
window implemented as a chip. It is not drawn to scale. The substrate may
be any quality of glass; inexpensive transparent borosilicate glass is
one option. The base (5) consists of transparent undoped silicon. N-type
silicon (6) is doped into this, and P-type silicon (7) is deposited onto
the N-type layer. The thickness of these layers are such that they are
transparent to visible light. The undoped and doped silicon can be
deposited by a variety of means such as LPCVD (low pressure chemical
vapor deposition), PECVD (plasma enhancedchemical vapor deposition), ALD
(atomic layer deposition), sputtering, or other similar processes.

[0026] The edge of the N-layer and the P-layer is a photovoltaically
active N-P diode juncture (12). Light (13) hitting this region causes an
electrical current consisting of electrons and holes. These are carried
away by the vias (8, 9) into the metal wires (10, 11). Light (13) hitting
these metal wires reflects away, while light (14) hitting the undoped
silicon passes through.

[0027] FIG. 3 shows a top view of the same device as in FIG. 2. FIG. 4
shows the how the metal wires (10, 11) in FIG. 2 and FIG. 3 traverse a
solar window implemented as a chip. (This is key, we need to define the
wires and the way to embed them, let me look this up.

[0028] FIG. 5 shows how an array of solar window chips (12) may be placed
on a glass backplane so that their metal wires line up. It is not drawn
to scale.

[0029] FIG. 6 shows a cross section of a part of a solar window
implemented on a sheet of glass. Visible light traverses the transparent
glass base (21). Stripes of N-paint (22), P-paint (23) and metal wire
paint (24 and 25) are all painted onto this glass base, in layers 22, 23,
24 and 25 obstruct light.

[0030] FIG. 7 shows the top view of a solar window implemented on a sheet
of glass. The devices here are the same as in FIG. 6.

[0031] FIG. 8 shows an example of the solar window implemented on a sheet
of glass, but only the glass (21), metal wire paint (24 and 25) and
rails. One rail (30) connects to metal wire paint (24) that connects to
the N-paint, and the other rail (31) connects to the metal wire paint
(25) that connects to the P-paint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Preferred Embodiment

[0032] In an aspect this invention is the Solar Window chip or "SW chip",
an integrated circuit [FIG. 2]. The SW chips are glued to a backplane of
transparent glass to give the structure rigidity. Adjacent SW chips on
the backplane abut so that their photovoltaic regions join, and their
wires join, as shown in FIG. 5.

[0034] In an aspect this invention is the Solar Window pane or "SW pane".
An SW pane consists of a sheet of transparent glass. Photovoltaically
active regions and wires are "painted", i.e. deposited in some fashion,
onto this glass, as in FIG. 6, FIG. 7 and FIG. 8. As shown in FIG. 8 the
glass (21) is painted to be a particular size. The edges of the glass
have metal paint rails that conduct the electricity generated away from
the window. The metal wire paint connecting to the P regions (25) all
connect to one rail (24) while the metal wire paint connecting to the N
regions (24) all connect to another rail (31). These rails conduct
electricity away from the solar window.

[0035] FIG. 7 shows that the one painted metal wire (24) connects to the
N-paint (22) which defines the painted N region, while another painted
metal wire (25) connects to the P-paint (23) which defines the painted P
region.

[0036] FIG. 6 shows a cross-section of one device of a solar window pant.
Here the base glass (21) has N-painted painted onto it (22), which
defines the N region. P-paint (23) is painted over the N-paint, creating
a photoactive region. Not abutting the P-paint (23) is a painted metal
wire (24) which conducts electricity away from the N-paint (22). Over the
P-paint (23) is a painted metal wire (25) which conducts electricity away
from the P-paint (25).

Third Preferred Embodiment

[0037] In an aspect this invention is Solar Window sheet, or "SW sheet".
It comprises a sheet of transparent plastic. Wires and photovoltaically
active regions are "painted", i.e. deposited in some fashion, onto this
plastic. Apart from the fact the underlying base is plastic instead of
glass and thus may be flexible, this preferred embodiment is identical to
the previous one.

[0042] We report the fabrication of a 50 nm half-pitch wire grid polarizer
with high performance using nanoimprint lithography. The device is a form
of aluminium gratings on a glass substrate whose size of 5.5 cm×5.5
cm is compatible with a microdisplay panel. A stamp with a pitch of 100
nm was fabricated on a silicon substrate using laser interference
lithography and sidewall patterning. The imprint and the aluminium
etching processes are optimized to realize uniform aluminium gratings
with aspect ratio of 4. The polarization extinction ratio of the
fabricated device is over 2000, with transmission of 85% at a wavelength
of 450 nm, which is the highest value ever reported. This work
demonstrates that nanoimprint lithography is a unique cost-effective
solution for nanopatteming requirements in consumer electronics
components

[0046] The synthesis of poly(9,9-dioctylfluorene) conjugated polymer
nanowires using the method of solution assisted wetting of nanoporous
alumina membrane templates is reported. Polymer nanowires (approx. 10 9
per template) with a diameter of approx. 200 nm are obtained.
Photoluminescence from isolated nanowires fluidically-aligned at glass
substrates is found to be dominated by emission from the planar
beta-phase of the polymer. The wires also exhibit polarized light
emission suggestive of axial alignment of beta-phase segments within the
nanowires. Dense arrays of aligned nanowires exhibiting anisotropic
emission are also demonstrated.

[0051] A silver nanowire array micropolarizer within an anodic alumina
membrane (AAM) was fabricated by anodization of pure Al foil and
electrodeposition of Ag, respectively. X-ray diffraction, scanning
election microscopy, and transmission electron microscopy investigations
reveal that the nanowires are essentially single crystals, and have an
average diameter of 90 nm. Spectrophotometer measurements show that the
silver nanowire arrays embedded in the AAM can only transmit vertically
polarized light to the wires. An extinction ratio of 25-26 dB and average
insertion loss of 0.77 dB in the wavelength range 1-2.2 μm were
obtained, respectively. Therefore the Ag nanowire/AAM can be used as a
wire-grid type polarizer